This invention relates to a convexly fluted reflector for a lamp such as a fog lamp, wherein the reflector itself distributes light in a desired, non-colliminated pattern.
It has been proposed in the past to utilize fluted reflectors to achieve non-uniform light distribution in a lamp. For example, Basillie U.S. Pat. No. 1,639,363 discloses an automotive lamp reflector having a number of distinct surface regions, including vertical sections or flutes which project light laterally. As pointed out at page 2, lines 105-110 of Basillie, the cross section of these sections 8, 9 is different from that of the corresponding portion of the general or basic curvature upon which the reflector is designed, and this cross section may be somewhat convex. The stated purpose of the sections 8, 9 is to illuminate the sides of the roadway with light rays that are held comparatively close to the ground so as not to create glare in the eyes of the driver of an approaching vehicle. However, Basillie gives no guidance as to the shape to be given the individual sections 8, 9.
Doorman U.S. Pat. No. 4,149,227 discloses a dental surgical lighting reflector having an ellipsoidal surface divided into sections. These sections are individually concave in cross section, as shown in FIG. 6, and each concave section defines a respective ellipsoid. The ellipsoids are rotated outwardly with respect to one another as shown in FIG. 6 to spread the reflected light along one axis, thereby enlarging the illuminated area. As shown in FIG. 12, the rotated ellipsoids may have focuses that are offset slightly with respect to one another. Alternately, as shown in FIG. 13, the ellipsoidal surfaces may be recalculated to ensure that all of the focuses coincide. Note the discussion at columns 6 and 7, and in particular the discussion at column 6, line 59 through column 7, line 18. The Doorman patent utilizes ellipsoids rather than paraboloids, and therefore causes reflected light to converge at the conjugate focus, and to diverge thereafter in both the horizontal and vertical directions. This dispersion pattern is unsuitable for many vehicular lamps.
My earlier U.S. Pat. No. 4,805,133 describes a lamp which defines a reflective surface comprising a series of paraboloid strips arranged side by side along a lateral direction and including a central paraboloid strip. Each of the paraboloid strips defines a respective focus, and all of the focuses substantially coincide at a selected point in space. The paraboloid strips are aimed in a plurality of non-parallel directions to laterally disperse reflected light originating at the selected point in space. Each of the paraboloid strips defines a respective focal length, and the focal lengths of paraboloid strips progressively farther from the central paraboloid strip are progressively greater. The focuses are selected such that adjacent paraboloid strips are matched in position and the reflective surface is substantially continuous. The reflector body preferably extends over all four quadrants, and the entire reflective surface provides a visually smooth appearance, without flutes of any type.
Finally, it has also been suggested in the past to provide a fog lamp reflector with an array of convex vertical flutes arranged side by side across the reflective surface. However, prior art approaches to fabricate such a lamp have, to the knowledge of the present inventor, been unsuccessful due to an inability to configure the surfaces of individual flutes properly to achieve the desired light distribution.
It is a primary object of this invention to provide such a vertically fluted fog lamp reflector with flutes that are configured appropriately so as to disperse light in a pattern appropriate for fog lamps.